Gold nanoparticle, surface plasmon resonance enhanced visible-light-driven debromination of tetrabromodiphenyl ethers by ZnIn2S4

2,2 ',4,4 '-tetrabromodiphenyl ether (BDE-47) is a highly toxic organic pollutant. Owing to the high structural stability, BDE-47 is difficult to be naturally decomposed. In this study, Au nanoparticles decorated flower-like ZnIn2S4 microspheres were successfully fabricated and applied for the rapid removal of BDE-47 driven by visible-light irradiation. It was revealed that 3 wt% Au-loaded ZnIn2S4 (Au/ZnIn2S4) has the highest removal rate for BDE-47 (0.90118 h-1). A study of the reaction path and mechanism shows that the bromine adjacent to the oxygen atom in BDE-47 tends to be removed via electron transfer. This is attributed to the band-gap excitation of ZnIn2S4, the surface plasmon resonance effect of the Au nanoparticles, and the Schottky junctions between them. Furthermore, density functional theory calculations show that the strong affinity between Au0 and the bromine atom adjacent to the oxygen atom in BDE-47 can lengthen the carbon-bromine bond and further weaken the bond upon the accumulation of electrons. This may be the main reason for the rapid debromination of BDE-47. This study provides a new perspective on the photocatalytic removal of moderately brominated polybrominated diphenyl ethers.